The "megachile pluto” is the largest of which of these insects?

The "megachile pluto" is a large Indonesian resin bee and is the largest known living bee species. It is also referred to as Wallace's giant bee or "raja ofu/rotu ofu" (king/queen of the bees in Indonesian).

The species was originally collected by Alfred Russel Wallace in 1858, and given the common name "Wallace's giant bee". It was thought to be extinct until it was rediscovered in 1981 by Adam C. Messer, an American entomologist.

He found six nests on the Indonesian islands of the North Moluccas namely Bacan, Halmahera and Tidore. The bees build communal nests inside active nests of tree-dwelling termites. It is among the 25 "most wanted" lost species that are the focus of Global Wildlife Conservation's "Search for Lost Species" initiative.

Wallace's giant bee is easily distinguished from other bees due to its large size and jaws, but also a notable white band on the abdomen.The species exhibits strong sexual dimorphism. A female may reach a length of 38 mm (1.5 in) and have a wingspan of 63.5 mm (2.5 in). The females have larger jaws than males. Males only grow to about 23 mm (0.9 in).

After 1981 the bee was not observed in the wild for 37 years. In 2018, two specimens were collected in Indonesia and sold on eBay. This highlighted the lack of protection that was afforded to this rare species. In 2019, a single female was found by the photographer Clay Bolt in Indonesia. This specimen was filmed and photographed before being released.